Problem: The sum of two numbers is $140$, and their difference is $36$. What are the two numbers?
Explanation: Let $x$ be the first number, and let $y$ be the second number. The system of equations is: ${x+y = 140}$ ${x-y = 36}$ Solve for $x$ and $y$ using elimination. Add the top and bottom equations together. $ 2x = 176 $ $ x = \dfrac{176}{2} $ ${x = 88}$ Now that you know ${x = 88}$ , plug it back into $ {x+y = 140}$ to find $y$ ${(88)}{ + y = 140}$ ${y = 52}$ You can also plug ${x = 88}$ into $ {x-y = 36}$ and get the same answer for $y$ ${(88)}{ - y = 36}$ ${y = 52}$ Therefore, the larger number is $88$, and the smaller number is $52$.